The tone used in vocal jazz is generally lighter. (I use “lighter” advisedly: the tone is not “breathy,” “thin,” or “unsupported.”) It’s one of the most misunderstood aspects of the style, and something that is constantly under scrutiny by vocalists and educators not conversant in the style.
Why is vocal jazz tone lighter? I would argue that there are several reasons.
- A lighter, generally senza vibrato tone allows richer harmonies to sound accurately. Vibrato can get in the way of the chord locking.
- A lighter, less formant-rich sound also improves tuning. Emphasizing more overtones can tend to created dissonances in the overtone series, and with microphones, we generally do not need to create a sound that carries long distances.
- The style grew out of a popular style typified by Ella Fitzgerald, Bing Crosby, Frank Sinatra, etc. It’s somewhat related to musical theatre, and to the pop singing of the 1930’s and 1940’s. This was more conversational, more intimate, less brassy and assertive.
I believe this sort of tone – lighter, but clear, potent, and well supported – has been adopted for vocal jazz and related styles for these and plenty of other reasons; I also believe that learning to sing with a wide variety of tones and stylistic approaches is absolutely essential to a career as a vocal musician in the 21st Century. Singers trained in vocal jazz are well-equipped to sing in a huge range of styles, including pop, R&B, rock, musical theatre, film music, contemporary choral, and on and on. As such, it’s a perfect counterpoint to traditional bel canto training.